1. Field of the Invention
The present invention relates to crypto equipment composed of an encoder at the transmitting side and a decoder at the receiving side, each respectively provided with a synchronization device for bit-by-bit encoding at the transmitting side and bit-by-bit decoding at the receiving side with respect to a bit stream having a high bit sequence frequency and representing a binary signal.
2. Description of the Prior Art
Crypto equipment of the type set forth above are disclosed, for example, in DE 29 20 589 B1. They serve the purpose of keeping information, for example, voice or data, that are to be transmitted secret. The bit stream representing the digital signal to be encoded can have a relatively high bit sequence rate when a sum signal transmission channel between two transmitting-receiving stations that represents exchanges is thereby involved.
As shown, for example, by the Jahrbuch der Deutschen Bundespost, Vol. 35, 1984, Verlag fuer Wissenschaft und Leben, Georg Heidecker, Bad Windsheim, pp. 334 and 335, several signals or, respectively, a plurality of signals are combined by multiplexing methods for the economical exploitation of transmission links, and what is referred to as a digital signal hierarchy is thus formed. In the fourth hierarchy level of the hierarchy structure on the 30-channel basic system, the bit stream of the first hierarchy level already exhibits a bit rate of 2048 Mbit and the fourth hierarchy level exhibits a bit rate of 139, 246 Mbit. In order to obtain optimally-small dimensions and an optimally-low power consumption of the required circuits, particularly for the utilization of such crypto equipment in mobile broadcast systems, integrated circuits in complementary metal-oxide-semiconductor (CMOS) technology are utilized. As has been shown, the operating speed of such integrated circuits constructed in CMOS technology cannot be arbitrarily increased. In order to encode, for example, a crypto equipment for encoding a digital sum signal of the fourth hierarchy level, the circuit required for this purpose can no longer be constructed in CMOS technology. On the contrary, one must switch to other technologies whose circuits exhibit a considerably higher power consumption. This is a considerable disadvantage given the utilization of such crypto equipment in the mobile broadcast area, since mobile broadcast equipment must be capable of operating independently of the mains voltage and the energy sources required for this purpose are to be kept sufficiently small for reasons of weight and dimensions.